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Gore-Tex® - The Inside Scoop
(Online Exclusive From Get Out There Magazine Jan/Feb 2010) A field report by Steven Cross, owner of Threads Lifestyle Recently I went undercover to investigate the truth or fiction about Gore-Tex® product. Well, not really undercover as they invited me down for a three-day seminar. But given the security they have in place and the detailed knowledge they shared it certainly felt like undercover at times. One of the first things I learned was that Gore-Tex® garments were only a small part of their world wide sales. Medical, electrical and industrial applications are much bigger. The fact is that Gore-Tex® products are used in many things where life and death quality is essential. For example, cardiovascular surgery and the NASA space suit. Over the years, I will admit to having been skeptical about Gore-Tex®. During the eighties I used enough of it to know that it often failed to meet expectations. However, today I am an unabashed fan and recommend it a lot. On my recent trip I learned even more about why I could trust my Gore-Tex® garments to perform. The science is pretty compelling. Gore-Tex® is a PTFE (polytetrafluoroethylene) chemical derivative first discovered in 1938. It can be manipulated into many versions. For example, by 1954 it had been engineered by a French engineer, Marc Gregoire, to coat frying pans and the famous Tefal product was born. In the Gore-Tex® version the PTFE is thermally and mechanically expanded into a microstructure of nodes interconnected by fibrils. The result is a membrane with about 9 billion pores per square inch. These pores are 20,000 times smaller than a drop of water but 700 times larger than a molecule of water vapor. Therein lies the key to the waterproof and breathable capability. (As an aside, Robert Gore was inducted into the Inventor’s Hall of Fame for this achievement.) Once the membrane was developed the folks at Gore went on to invent a lamination process. The early Gore product (1981 to 1990 or so) really did have problems but the lamination process has been greatly improved since then and is a closely guarded secret. Other waterproof-breathable products work in similar fashion – porosity that allows flow one way but not the other - but they are typically coatings or coating laminates and just as one sees inconsistency in a painted wall, so to does inconsistency occur in most factory coatings. This is especially true for the ones at lower price points. The bottom line is that while all waterproof breathable products work the Gore-Tex® membrane serves up a bigger comfort range and a certain consistency. A hot issue around this “claim” is the way testing and measurements are done and reported. The folks at Gore like to make the point that their testing is real world and user centric while many other products, claiming to be as good, use testing that is more static and limited. A day spent touring all the testing that Gore does is certainly convincing. So where does all the doubt and confusion come from? After all where there is smoke there must be fire, right? The first source of confusion is thresholds and standards. The baseline for being able to say a product is waterproof came from tests and standards first created during World War II. For example, most skiwear sold today cites a standard of 3,000 to 10,000 mm for waterproof. (That refers to the depth in mm of a column of water suspended above the cloth before leakage occurs.) The lightest made Gore-Tex® version – which is their Pac-lite® - tests out on at 28,000 mm. In other words, it does not take much for a fabric to test as waterproof but in real life it might not work as well as the buyer expects. When it comes to breathability the testing is even more confusing. Many tests yield strong results but the reality of what happens in the field is quite different. For me, this is where the confusion comes from statements one often hears in stores such as “ same as Gore-Tex® but cheaper”. While the alternate product meets some standards and does work, the truth is it will not work as well as Gore-Tex®. I have proven this to myself many times in the field. A second source of confusion derives from history and expectations. Early Gore-Tex® product simply did not perform that well and while the product of today is greatly improved the old stories are still out there – now as myth rather than fact. Unrealistic expectations also create unhappy stories. For example, no garment can stop you from sweating and yet I often hear customers use that phrase to describe what it is they are looking for. The reality is that if we did not sweat we would die. The most important thing to understand about breathability is that in order for any garment to pass the moisture rich air your body creates, there has to be a porous fabric in place and a significant temperature differential from the outside. Essentially what is needed is a heat pump – hotter air inside your jacket that expands and drives itself out through the pores of the membrane or coating. Without that significant heat differential there is no way the garment can pass moisture out. If you don’t think Gore-Tex® breathes try wearing a plastic bag for comparison. But if you are going to the tropics you might be better off just getting wet or using an umbrella. Simply put, Gore-Tex®, or any waterproof-breathable for that matter, works best in wet or alpine environments, where the outside temperature is significantly lower than inside your jacket. A third source of confusion stems from the lack of understanding around DWR and the care and cleaning for Gore-Tex® garments. Durable water repellant coating (DWR) is a factory finish that is applied to the surface of all waterproof garments. This finish enhances the surface beading of rainwater so it runs off the fabric easily. Without this finish in place breathablity is impacted because face fabric holds on to water within its fibers. Interestingly enough most people who experience a DWR failure do not sense it as a breathabilty issue but rather as a waterproof issue. This is because they interpret the “wet spot” which is discolored and cold, as a leak, which it isn’t. The good news is that the DWR finish can be easily restored with either a wash-in product or a spray-on product. The spray, while a bit less convenient, is the better performance choice for it ensures application where it should occur. The wash in product works but it can end up applying DWR to the inside of your garment thereby impacting breathability. For Gore-Tex® product to work well it must be frequently washed and then dried in a dryer. Keeping it clean prevents pores from being plugged and the DWR finish needs heat to reactivate and redistribute itself over the garment. (If you are seeing “wet out” spots on your garment, be sure to wash and dry it prior to spending the time and money on reapplying a DWR finish. The factory DWR might not be evenly distributed rather than gone.) The Gore-Tex® membrane itself is inert and unaffected by temperatures from as low as -148F to as high as 324F. So washing and drying in a dryer is certainly okay and will not harm the membrane. Most of the customers I have helped with Gore-Tex® complaints over the years have not followed the care instructions. By the way dry-cleaning does not affect Gore-Tex® but it won’t reactivate the DWR and it might damage the face fabric. For those reasons dry-cleaning is not recommended. One the biggest reasons Gore-Tex® product is reliable today is the fact that Gore has taken on the role of policing the design and manufacture of any product using their membrane. While this reality has not always played well with the brands, which would often like more freedom in design, the reality is that quality is assured through this process. Here is how it works. Any brand wanting to do a Gore-Tex® garment submits its details for design, fabrics and components to Gore for approval. Upon approval the face fabric is sent to one of three Gore plants in the world for lamination. The brand itself never touches, sees or deals with the actual Gore-Tex® membrane. The laminated face fabric is then shipped to Gore approved factories for assembly and seam taping. By implementing such a rigorous approach to quality Gore - and the brands using it in products - can truly stand by the “Guaranteed to Keep You Dry” warranty attached to all Gore-Tex® products. A Gore-Tex® garment represents a unique product in both the science and the partnership that creates it. I like to point out to people that Hillary climbed Everest in a wax coated cotton anorak. High tech gear and clothing is not always essential to enjoyment or success. On the other hand I truly do believe that there is no bad weather, just the wrong clothing. All the waterproof breathable products work but I am utterly convinced that Gore-Tex® works best and is the most reliable. Got question or ideas for future columns? Send them to me care of Get Out There magazine and I will do my best to get you information and answers. |
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